:root {
  color-scheme: light;
  --paper: #fbf8f0;
  --paper-deep: #f2eadb;
  --paper-warm: #eadcc5;
  --ink: #20372f;
  --ink-soft: #4e5d55;
  --brand: #315b46;
  --brand-deep: #244334;
  --sage: #6a7f63;
  --teal: #386c6b;
  --cinnabar: #b76e52;
  --line: #d8ccba;
  --white: #fffdf8;
  --shadow: 0 24px 70px rgba(46, 55, 47, 0.14);
  --radius: 8px;
  font-family: "Noto Sans SC", "Microsoft YaHei", "PingFang SC", sans-serif;
  background: var(--paper);
  color: var(--ink);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    linear-gradient(115deg, rgba(49, 91, 70, 0.12), transparent 28%),
    linear-gradient(20deg, rgba(183, 110, 82, 0.08), transparent 34%),
    var(--paper);
  color: var(--ink);
}

body.is-viewer-open {
  overflow: hidden;
}

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

body::before {
  position: fixed;
  inset: 0;
  pointer-events: none;
  content: "";
  opacity: 0.34;
  background-image:
    linear-gradient(rgba(32, 55, 47, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(32, 55, 47, 0.026) 1px, transparent 1px);
  background-size: 38px 38px;
}

a {
  color: inherit;
  text-decoration: none;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px clamp(18px, 5vw, 68px);
  border-bottom: 1px solid rgba(216, 204, 186, 0.72);
  background: rgba(251, 248, 240, 0.88);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 154px;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 10px;
  background: var(--brand);
  color: var(--white);
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 20px;
  font-weight: 800;
}

.brand strong,
.site-footer strong {
  display: block;
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 18px;
  letter-spacing: 0;
}

.brand small {
  display: block;
  margin-top: 1px;
  color: var(--ink-soft);
  font-size: 12px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 26px);
  color: var(--ink-soft);
  font-size: 14px;
  white-space: nowrap;
}

.site-nav a {
  transition: color 180ms ease, transform 180ms ease;
}

.site-nav a:hover {
  color: var(--brand);
}

.site-nav a:active,
.button:active,
.path-panel a:active {
  transform: translateY(1px);
}

.nav-product-link {
  padding: 9px 14px;
  border: 1px solid rgba(49, 91, 70, 0.22);
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.72);
  color: var(--brand);
  font-weight: 700;
}

main {
  position: relative;
}

.hero-section,
.paths-section,
.screens-section,
.features-section,
.updates-section,
.final-cta,
.site-footer {
  width: min(1180px, calc(100vw - 36px));
  margin: 0 auto;
}

.hero-section {
  display: grid;
  grid-template-columns: minmax(0, 0.86fr) minmax(420px, 1.14fr);
  gap: clamp(34px, 6vw, 84px);
  align-items: center;
  min-height: min(880px, calc(100dvh - 76px));
  padding: clamp(56px, 9vw, 112px) 0 clamp(58px, 8vw, 96px);
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  letter-spacing: 0;
}

h1 {
  max-width: 9.2em;
  margin-bottom: 22px;
  font-size: clamp(44px, 7vw, 84px);
  line-height: 1.05;
  font-weight: 900;
}

.hero-title {
  max-width: 10.5em;
  margin-bottom: 22px;
  font-size: clamp(34px, 4.8vw, 56px);
  line-height: 1.12;
  font-weight: 900;
}

.hero-lead {
  max-width: 670px;
  margin-bottom: 28px;
  color: var(--ink-soft);
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.9;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin-bottom: 30px;
}

.hero-actions.centered {
  justify-content: center;
  margin: 24px 0 0;
}

.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 0 21px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 800;
  transition: transform 180ms ease, background 180ms ease, border-color 180ms ease;
}

.button.primary {
  background: var(--brand);
  color: var(--white);
  box-shadow: 0 16px 36px rgba(49, 91, 70, 0.22);
}

.button.primary:hover {
  background: var(--brand-deep);
}

.button.secondary {
  border: 1px solid rgba(49, 91, 70, 0.28);
  background: rgba(255, 253, 248, 0.78);
  color: var(--brand);
}

.button.secondary:hover {
  border-color: rgba(49, 91, 70, 0.46);
  background: var(--white);
}

.hero-facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  max-width: 740px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--line);
}

.hero-facts div {
  min-width: 0;
  padding: 16px;
  background: rgba(255, 253, 248, 0.72);
}

.hero-facts dt {
  margin-bottom: 8px;
  color: var(--brand);
  font-weight: 900;
}

.hero-facts dd {
  margin: 0;
  color: var(--ink-soft);
  font-size: 13px;
  line-height: 1.6;
}

.hero-board {
  position: relative;
  min-height: 570px;
}

.paper-stack {
  position: absolute;
  display: block;
  border: 1px solid rgba(49, 91, 70, 0.18);
  border-radius: var(--radius);
  background: var(--white);
  box-shadow: var(--shadow);
}

.source-paper {
  top: 14px;
  left: 0;
  width: min(64%, 420px);
  padding: 28px;
  transform: rotate(-2deg);
}

.source-paper p {
  margin: 0 0 14px;
  color: var(--ink-soft);
  font-size: 17px;
  line-height: 1.9;
}

.source-paper i {
  display: block;
  width: 42%;
  height: 5px;
  margin-top: 24px;
  border-radius: 999px;
  background: var(--cinnabar);
}

.vocab-paper {
  top: 172px;
  right: 0;
  width: min(52%, 340px);
  padding: 24px;
  background: #f6f2e8;
  transform: rotate(2deg);
}

.vocab-paper ul {
  display: grid;
  gap: 12px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}

.vocab-paper li {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(49, 91, 70, 0.13);
  color: var(--ink-soft);
}

.vocab-paper strong {
  color: var(--teal);
}

.workbook-paper {
  right: 10%;
  bottom: 10px;
  width: min(62%, 420px);
  padding: 28px;
  transform: rotate(-1deg);
}

.step-label {
  display: inline-flex;
  align-items: center;
  margin-bottom: 8px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 900;
}

.workbook-row {
  height: 12px;
  margin-top: 16px;
  border-radius: 999px;
  background: rgba(49, 91, 70, 0.18);
}

.workbook-row.short {
  width: 64%;
}

.review-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin-top: 24px;
}

.review-grid span {
  height: 34px;
  border: 1px solid rgba(49, 91, 70, 0.18);
  border-radius: 6px;
  background: rgba(106, 127, 99, 0.12);
}

.flow-line {
  position: absolute;
  top: 112px;
  right: 116px;
  width: 46%;
  height: 276px;
  border-top: 1px solid rgba(56, 108, 107, 0.34);
  border-right: 1px solid rgba(56, 108, 107, 0.34);
  border-radius: 0 48px 0 0;
}

.paths-section,
.screens-section,
.features-section,
.updates-section,
.final-cta {
  padding: clamp(52px, 8vw, 94px) 0;
}

.section-heading {
  display: grid;
  grid-template-columns: minmax(0, 0.8fr) minmax(280px, 0.9fr);
  gap: clamp(22px, 5vw, 72px);
  align-items: end;
  margin-bottom: 34px;
}

.section-heading.compact {
  display: block;
  max-width: 720px;
}

.section-heading h2,
.final-cta h2 {
  margin-bottom: 0;
  font-size: clamp(30px, 4.6vw, 54px);
  line-height: 1.18;
}

.section-heading p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 16px;
  line-height: 1.9;
}

.path-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 18px;
}

.path-panel {
  position: relative;
  min-height: 420px;
  padding: clamp(28px, 4vw, 46px);
  overflow: hidden;
  border: 1px solid rgba(216, 204, 186, 0.9);
  border-radius: var(--radius);
  background: rgba(255, 253, 248, 0.74);
}

.path-panel.generate {
  background: linear-gradient(145deg, rgba(255, 253, 248, 0.92), rgba(234, 220, 197, 0.64));
}

.path-panel.reading {
  margin-top: 52px;
  background: linear-gradient(145deg, rgba(49, 91, 70, 0.94), rgba(32, 55, 47, 0.96));
  color: var(--white);
}

.path-panel h3 {
  margin-bottom: 18px;
  font-size: clamp(28px, 4vw, 42px);
}

.path-panel p {
  max-width: 600px;
  color: inherit;
  opacity: 0.82;
  line-height: 1.85;
}

.path-panel ol {
  display: grid;
  gap: 11px;
  margin: 28px 0;
  padding: 0;
  list-style: none;
}

.path-panel li {
  position: relative;
  padding-left: 24px;
  color: inherit;
  opacity: 0.88;
}

.path-panel li::before {
  position: absolute;
  left: 0;
  top: 0.68em;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--cinnabar);
  content: "";
}

.path-panel.reading li::before {
  background: var(--paper-warm);
}

.path-panel a {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  margin-top: 4px;
  padding: 0 18px;
  border-radius: 999px;
  background: var(--brand);
  color: var(--white);
  font-weight: 900;
  transition: transform 180ms ease, background 180ms ease;
}

.path-panel.reading a {
  background: var(--white);
  color: var(--brand);
}

.path-index {
  position: absolute;
  right: 28px;
  top: 24px;
  color: currentColor;
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 70px;
  line-height: 1;
  opacity: 0.12;
}

.screen-flow {
  --screen-image-height: clamp(260px, 22vw, 360px);
  display: flex;
  flex-wrap: nowrap;
  justify-content: safe center;
  gap: 18px;
  align-items: flex-start;
  margin-top: 34px;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0 0 14px;
  scroll-snap-type: x proximity;
  scrollbar-color: rgba(49, 91, 70, 0.36) rgba(216, 204, 186, 0.28);
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}

.screen-groups {
  display: grid;
  gap: clamp(28px, 5vw, 54px);
  margin-top: 34px;
}

.screen-group {
  display: grid;
  gap: 18px;
}

.screen-group-heading {
  display: grid;
  grid-template-columns: minmax(0, 0.78fr) minmax(260px, 0.9fr);
  gap: 22px;
  align-items: end;
}

.screen-group-heading h3 {
  margin: 0;
  font-size: clamp(24px, 3vw, 36px);
  line-height: 1.22;
}

.screen-group-heading p {
  margin: 0;
  color: var(--ink-soft);
  line-height: 1.8;
}

.screen-flow.tool-flow {
  margin-top: 0;
}

.screen-flow.reading-flow {
  margin-top: 0;
}

.screen-card {
  position: relative;
  display: inline-grid;
  flex: 0 0 auto;
  width: fit-content;
  margin: 0;
  overflow: visible;
  background: transparent;
  scroll-snap-align: start;
}

.screen-card img {
  display: block;
  width: auto;
  height: var(--screen-image-height);
  border: 1px solid rgba(216, 204, 186, 0.9);
  border-radius: var(--radius);
  background: var(--paper-deep);
  box-shadow: 0 10px 26px rgba(46, 55, 47, 0.08);
  cursor: zoom-in;
}

.screen-placeholder {
  display: grid;
  position: absolute;
  inset: 18px 18px 86px;
  place-items: center;
  align-content: center;
  gap: 8px;
  border: 1px dashed rgba(49, 91, 70, 0.28);
  border-radius: 6px;
  background:
    linear-gradient(135deg, rgba(49, 91, 70, 0.08), transparent 46%),
    rgba(242, 234, 219, 0.76);
  color: var(--brand);
  text-align: center;
}

.screen-placeholder span {
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 20px;
  font-weight: 900;
}

.screen-placeholder small {
  color: var(--ink-soft);
  font-family: "Cascadia Mono", "Consolas", monospace;
  font-size: 12px;
}

.screen-card:not(.is-missing) .screen-placeholder {
  display: none;
}

.screen-card.is-missing img {
  display: none;
}

.image-viewer {
  position: fixed;
  inset: 0;
  z-index: 30;
  display: grid;
  place-items: center;
  padding: clamp(18px, 4vw, 48px);
  background: rgba(26, 37, 33, 0.78);
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
}

.image-viewer.is-open {
  opacity: 1;
  pointer-events: auto;
}

.image-viewer-stage {
  display: grid;
  width: 100%;
  height: 100%;
  place-items: center;
  overflow: hidden;
  touch-action: none;
}

.image-viewer-stage img {
  display: block;
  max-width: min(1280px, 92vw);
  max-height: 88vh;
  border-radius: var(--radius);
  box-shadow: 0 28px 86px rgba(0, 0, 0, 0.28);
  cursor: zoom-out;
  transform-origin: center center;
  transition: transform 180ms cubic-bezier(0.16, 1, 0.3, 1);
  user-select: none;
  will-change: transform;
}

.image-viewer.is-dragging .image-viewer-stage img {
  cursor: grabbing;
  transition: none;
}

.image-viewer-close {
  position: fixed;
  top: 18px;
  right: 18px;
  z-index: 31;
  min-height: 40px;
  padding: 0 14px;
  border: 1px solid rgba(255, 253, 248, 0.34);
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.9);
  color: var(--brand-deep);
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.feature-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--line);
}

.feature-list article {
  min-height: 250px;
  padding: 26px;
  background: rgba(255, 253, 248, 0.76);
}

.feature-list h3 {
  margin-bottom: 14px;
  font-size: 22px;
}

.feature-list p,
.update-timeline span,
.site-footer p {
  color: var(--ink-soft);
  line-height: 1.85;
}

.update-timeline {
  display: grid;
  gap: 0;
  margin: 34px 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
  list-style: none;
}

.update-timeline li {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr);
  gap: 28px;
  padding: 22px 0;
  border-bottom: 1px solid var(--line);
}

.update-timeline time {
  color: var(--cinnabar);
  font-family: "Cascadia Mono", "Consolas", monospace;
  font-size: 14px;
  font-weight: 800;
}

.final-cta {
  text-align: center;
}

.final-cta h2 {
  margin: 0 auto;
  max-width: 760px;
}

.site-footer {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 28px;
  padding: 34px 0 46px;
  border-top: 1px solid var(--line);
}

.site-footer p {
  max-width: 560px;
  margin: 8px 0 0;
  font-size: 14px;
}

.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 14px 20px;
  color: var(--ink-soft);
  font-size: 14px;
}

.site-footer a:hover {
  color: var(--brand);
}

@media (max-width: 980px) {
  .site-nav a:not(.nav-product-link) {
    display: none;
  }

  .hero-section,
  .section-heading,
  .screen-group-heading,
  .path-grid,
  .screen-flow,
  .feature-list,
  .site-footer {
    grid-template-columns: 1fr;
  }

  .hero-section {
    min-height: auto;
  }

  .hero-board {
    min-height: 560px;
  }

  .source-paper {
    width: 72%;
  }

  .vocab-paper {
    width: 58%;
  }

  .workbook-paper {
    right: 0;
    width: 70%;
  }

  .path-panel.reading {
    margin-top: 0;
  }

  .screen-flow {
    --screen-image-height: 320px;
  }

  .feature-list article {
    min-height: auto;
  }

  .site-footer nav {
    justify-content: flex-start;
  }
}

@media (max-width: 640px) {
  .site-header {
    padding: 14px 16px;
  }

  .brand {
    min-width: 0;
  }

  .brand small {
    display: none;
  }

  .site-nav {
    font-size: 13px;
  }

  .hero-section,
  .paths-section,
  .screens-section,
  .features-section,
  .updates-section,
  .final-cta,
  .site-footer {
    width: min(100vw - 28px, 1180px);
  }

  h1:not(.sr-only) {
    max-width: none;
    font-size: clamp(38px, 12vw, 52px);
  }

  .hero-title {
    max-width: none;
    font-size: clamp(32px, 9vw, 44px);
  }

  .hero-facts,
  .update-timeline li {
    grid-template-columns: 1fr;
  }

  .hero-facts div {
    padding: 14px;
  }

  .hero-board {
    min-height: 520px;
  }

  .paper-stack {
    position: relative;
    inset: auto;
    width: 100%;
    transform: none;
  }

  .source-paper,
  .vocab-paper,
  .workbook-paper {
    width: 100%;
    margin-bottom: 14px;
  }

  .flow-line {
    display: none;
  }

  .path-panel {
    min-height: auto;
    padding: 24px;
  }

  .path-index {
    font-size: 48px;
  }

  .screen-flow {
    --screen-image-height: 260px;
  }

  .screen-placeholder {
    inset: 14px 14px 88px;
  }

  .site-footer {
    display: grid;
  }
}